In various open, endoscopic, and/or laparoscopic surgeries it may be necessary to coagulate, seal, and/or fuse tissue, even before applying a plurality of surgical fasteners or staples to the body tissue, to insure reliable seal. To do that, the tissue is captured within an end effector of a surgical instrument in order to cause thermal effects within the tissue. The thermogenic energy also strengthens tissue in proximity to a staple line and knife cut line and provides hemostasis along the staple and cut lines formed by the staples and a knife blade during surgical stapling. The use of thermogenic energy provides short-term hemostasis and sealing, and reduces or prevents the staple line and the cut line bleeding, while the stapling features provide short and long-term tissue strength and hemostasis.
In general, the delivery of heat energy to the captured tissue elevates the temperature of the tissue and, as a result, the energy can at least partially denature proteins within the tissue. The proteins, such as collagen, for example, may be denatured into a proteinaceous amalgam that intermixes and fuses, or “welds”, together as the proteins renature.
It would be desirable to have an end effector structure of stapling devices combining the structural and functional aspects of stapling instruments and heat tissue compressed between jaws of end effector to desired temperature to improved hemostasis by using thermogenic energy to cause coagulation or cauterization and surgical fasteners to staple the tissue, either before, during or after the use of thermogenic energy.
Prior usage of RF energy to provide tissue hemostasis prior to surgical stapling was not reliable, because tissue heating by RF energy depends of tissue parameters (e.g. wet versus dry), and often during RF heating, tissue charring and smoke generation will occur and because of tissue sticking to the RF electrodes, with a chance that treated area will be disrupted and bleeding can occur.
Usage of known resistive heating technology in surgical staplers very problematic because of significant thermal inertia of this type of heaters, which leads to a long heating and cooling time. Further problems arise from the resistance heater heating up the tissue only by conventional heat exchange, which can be very long process because of tissue low heat conductivity, which will lead to long heating time, especially for thick tissue, which may also influence penetration and uniformity of heating throughout the tissue.